The Nikolayev Gambit
The "Nikolayev Gambit" is a hybrid of the Blumenfeld and Benko Gambits. I believe I have played this continuation at the master level more than anyone else. To justify this new classification we need to survey related opening theory.
A. 1.d4 Nf6 2.c4 e6 3.Nf3 c5 4.d5 b5 = Blumenfeld Gambit
B. 1.d4 Nf6 2.c4 c5 3.d5 b5 4.cxb5 a6 = Benko-Volga Gambit
C. 1.d4 Nf6 2.c4 c5 3.d5 b5 4.cxb5 a6 5.bxa6 e6 6.Nc3 exd5 7.Nxd5 Nxa6!? = Nikolayev Gambit
In the middle 1980's I was eager to find a new aggressive weapon against 1.d4. I considered the Blumenfeld Gambit (1.d4 Nf6 2.c4 e6 3.Nf3 c5 4.d5 b5). Its "defect" was that White could avoid it with 3.Nc3 or 3.g3, but its ideas in general attracted me. So I considered the "accelerated" Blumenfeld. The positions which occurred after 1.d4 Nf6 2.c4 c5 3.d5 b5 4.cxb5 e6 5.Nc3 exd5 6.Nxd5 Bb7 7.Nxf6 (7.Nc3 d5) Qxf6 looked okay for Black. Yet there was there a refutation, namely 7.e4! Black will be crushed if he plays 7...Nxe4, which has been proven in many games. If Black doesn't take the e4-pawn, he is strategically lost. This line simply doesn’t work.
The Benko-Volga Gambit is a well-established and strong response to 1.d4. Black's queen-side counterplay is lasting and solid with his better piece mobility. As before, White has many ways of safely declining the pawn. After 3...b5, white can decline with 4.a4, 4.Qc2, 4.Nd2, or even 4.Nf3 offering to transpose into the Blumenfeld after 4...e6 . On move five, also, after 4.cxb5 a6, white can safely decline the gambit with 5.Nc3, 5.b6, 5.e3, or 5.f3 though none yields an advantage for White. Somehow I was not much interested in the solid Benko-Volga.
I felt that Black would be much better off if his queenside was developed. With this thought I created the "Nikolayev Gambit." The core idea of this dynamic set-up revolves around active piece play rather than elaborate pawn structures coupled with long term strategic maneuvering. The first moves are similar to the Benko-Volga Gambit. However the ideas behind them are different. The main features of the accepted Benko-Volga are bishops on a6 and g7 (after ...g6), while in the Nikolayev Gambit this never occurs. The main features of the Nikolayev Gambit are ...a6 first (as in the Benko-Volga), ...e6 (as in the Blumenfeld), and ...Nxa6 (never ...Bxa6), quickly followed by ...Nb4. The dark square bishop comes to g7 in some lines only after ...gxf6.